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-rw-r--r--software/vectored_interrupts/vectored_interrupts.c66
1 files changed, 60 insertions, 6 deletions
diff --git a/software/vectored_interrupts/vectored_interrupts.c b/software/vectored_interrupts/vectored_interrupts.c
index 06b9620..cb6a864 100644
--- a/software/vectored_interrupts/vectored_interrupts.c
+++ b/software/vectored_interrupts/vectored_interrupts.c
@@ -23,6 +23,19 @@ typedef void (*interrupt_function_ptr_t) (void);
//interrupt handlers
interrupt_function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS];
+//ecall countdown
+uint32_t ecall_countdown;
+//ecall macro used to store argument in a0
+#define ECALL(arg) ({ \
+ register uintptr_t a0 asm ("a0") = (uintptr_t)(arg); \
+ asm volatile ("ecall" \
+ : "+r" (a0) \
+ : \
+ : "memory"); \
+ a0; \
+})
+
+
const char * instructions_msg = " \
\n\
SIFIVE, INC.\n\
@@ -33,6 +46,7 @@ the E31/E51 Coreplex. The vector table is defined in \n\
bsp/env/ventry.S \n\
Button 0 is a global external interrupt routed to the PLIC.\n\
Button 1 is a local interrupt.\n\
+Every 10 seconds, an ECALL is made. \n\
\n";
void print_instructions() {
@@ -42,11 +56,17 @@ void print_instructions() {
}
void set_timer() {
+ static uint64_t then = 0;
volatile uint64_t * mtime = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIME);
volatile uint64_t * mtimecmp = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIMECMP);
- uint64_t now = *mtime;
- uint64_t then = now + 1*RTC_FREQ;
+ if(then != 0) {
+ //next timer irq is 1 second from previous
+ then += 1*RTC_FREQ;
+ } else{ //first time setting the timer
+ uint64_t now = *mtime;
+ then = now + 1*RTC_FREQ;
+ }
*mtimecmp = then;
set_csr(mie, MIP_MTIP);
@@ -59,6 +79,9 @@ void handle_m_time_interrupt(){
clear_csr(mie, MIP_MTIP);
+ //increment ecall_countdown
+ ecall_countdown++;
+
// Set Green LED
if(onoff) {
GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << GREEN_LED_OFFSET) ;
@@ -67,8 +90,8 @@ void handle_m_time_interrupt(){
GPIO_REG(GPIO_OUTPUT_VAL) &= ~((0x1 << GREEN_LED_OFFSET)) ;
onoff=1;
}
- set_timer();
+ set_timer();
//re-enable button1 irq
set_csr(mie, MIP_MLIP(LOCAL_INT_BTN_1));
@@ -76,9 +99,30 @@ void handle_m_time_interrupt(){
/*Synchronous Trap Handler*/
/*called from bsp/env/ventry.s */
-void handle_sync_trap( ) {
- write(1, "vUnhandled Trap:\n", 16);
+void handle_sync_trap(uint32_t arg0) {
+ uint32_t exception_code = read_csr(mcause);
+
+ //check for machine mode ecall
+ if(exception_code == CAUSE_MACHINE_ECALL) {
+ //reset ecall_countdown
+ ecall_countdown = 0;
+
+ //ecall argument is stored in a0 prior to
+ //ECALL instruction.
+ printf("ecall from M-mode: %d\n",arg0);
+
+ //on exceptions, mepc points to the instruction
+ //which triggered the exception, in order to
+ //return to the next instruction, increment
+ //mepc
+ unsigned long epc = read_csr(mepc);
+ epc += 4; //return to next instruction
+ write_csr(mepc, epc);
+
+ } else{
+ printf("vUnhandled Trap:\n");
_exit(1 + read_csr(mcause));
+ }
}
/*Entry Point for PLIC Interrupt Handler*/
@@ -186,6 +230,8 @@ void led_init() {
int main(int argc, char **argv)
{
+ uint32_t ecall_count = 0;
+
//setup default global interrupt handler
for (int gisr = 0; gisr < PLIC_NUM_INTERRUPTS; gisr++){
g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS] = invalid_global_isr;
@@ -197,6 +243,9 @@ int main(int argc, char **argv)
b0_irq_init();
b1_irq_init();
+ //initialize ecall_countdown
+ ecall_countdown = 0;
+
// Set up machine timer interrupt.
set_timer();
@@ -207,8 +256,13 @@ int main(int argc, char **argv)
set_csr(mstatus, MSTATUS_MIE);
- while(1){
+ while(1){
asm volatile ("wfi");
+ //check if ecall_countdown is 10
+ if(ecall_countdown == 10) {
+ ECALL(ecall_count++);
+ }
+ //otherwise wfi
}
return 0;